The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in the present disclosure and are not admitted to be prior art by inclusion in this section.
In existing 3GPP LTE networks, the CRS may be transmitted from an eNodeB (eNB) to a user equipment (UE). In embodiments, the CRS may be used to support channel quality indicator (CQI) reporting and demodulation. Additionally, the CRS may be used to support reference signal received power (RSRP) and reference signal received quality (RSRQ) measurements for handover or for Radio Resource Management (RRM) purposes. The CRS may be transmitted as a quadrature phase shift keying (QPSK) modulated signal.
In embodiments, the CRS may be broadcast in each subframe of a radio frame and may have a periodicity of 10 milliseconds (ms). That is, the CRS may repeat every 10 milliseconds. In common LTE networks, a radio frame of the LTE network may generally have a length of 10 ms. Because the CRS may have a periodicity of 10 ms, the CRS may repeat at each radio frame, and the same patterns of the CRS may be broadcast at each subframe of the radio frame. In these embodiments, if a CRS of one eNB conflicts with or causes interference to a CRS of another eNB, or a CRS of another port of the eNB, on the same frequency Resource Elements (REs) in a subframe of the radio frame, then this interference may be repeated at every radio frame of the network.